John L. Sullivan, in full John Lawrence Sullivan, byname The Great John L., or The Boston Strong Boy, (born Oct. 15, 1858, Roxbury, Mass., U.S. died Feb. 2, 1918, Abington, Mass.), American professional boxer, one of the most popular heavyweight champions and a symbol of the bareknuckle era of boxing. Sullivan began to fight professionally in 1878 after briefly studying at Boston College. On Feb. 7, 1882, at Mississippi City, Miss., he knocked out Paddy Ryan in the ninth round of a bareknuckle fight for the heavyweight championship. His 75-round knockout of Jake Kilrain at Richburg, Miss., July 8, 1889, was